Many automatic lighting devices are known which provide a number of benefits and conveniences. However, these devices suffer from a variety of limitations.
For example, U.S. Pat. No. 4,198,574 discloses a timing control circuit which turns a light on and off over time to give a dwelling the appearance of occupancy. However, this device must be set on a day-to-day basis. Further, the device is responsive to mechanical settings and thus has limited on and off patterns. In addition, the device requires a photocell input to turn on under low light conditions.
U.S. Pat. No. 4,349,748 discloses a timer and power control system which responds to successive advancement of a rotatable control dial. This system is also limited because it is essentially a mechanically controlled system.
U.S. Pat. No. 3,739,226 discloses an emergency light circuit for mounting to an electrical wall outlet. This device replaces a wall switch and uses rechargeable batteries to energize a light when the main power fails or the ambient light intensity falls below a predetermined level. This device is also photocell responsive.
Thus, it can be seen that known automatic devices suffer from several disadvantages. First, these devices have previously been responsive to essentially mechanical settings and thus have been relatively limited in the number of on/off patterns available. In particular, these devices have had a limited variety of on/off settings available during the day and have had even less flexibility in varying their on/off patterns from day-to-day.
In addition, these devices have required photocell inputs for responding to changing light levels. However photocell arrangements increase the cost and complexity of the lighting control system, must sometimes be located remote from the rest of the switching system itself, and do not add a high degree of flexibility or turn on/turn off accuracy in response to changing time.
Moreover, these systems have not been capable of automatically adjusting to varying light conditions caused by sunset variations based on geographical location, the advancing days of the year, or daylight savings time changes.